Phase shifting circuit



Jan. 21, 1941. cs. w. GARMAN 2,229,449

PHASE SHIFTING CIRCUIT Filed Dec. 14, 19s? Figl.

-nuu'uguun0'0 Inventor: George W. (Barn-nan His Attorney. 7

Patented Jan. 21, 1941 UNITED STATES PATENT OFFICE.

PHASE SHIF'HNG CIRCUIT George W. Garman, Scotia, N. Y., assignor to General Electric Company, a corporation of New York Application December-14, 1937, Serial No. 179,710 Claims. (Cl. 172-238) My invention relates to electric circuits and interposed between the pair of circuits and the more particularly to electric circuits for shittother terminal connection of the winding. The ing the phase of an alternating potential derived voltage divider-includes a resistance having terfrom a source with respect to the potential of minals connected to the capacitance and the in- 5 t t Source, ductance, and the resistance is provided with an 5 My invention is of general application in elecintermed ate point which s c ected to the trio control and regulating systems, although it is other terminal connection. An adjustable or particularly adapted for use in connection with movable contact member is provided in operative electric power converting apparatus for transrelation with the resistance of the voltage dividmitting energy between direct current and alterer to control the phase of the alternating voltage 10 nating current systems, or between alternating impressed on an output circuit which is connectcurrent systems, by the use of electric valves. In ed between the movable contact member and the such applications it is customary to control the intermediate connection of the winding. In one transmission of power between the direct current mbodiment of y ve o t adjustable and t alternating current systems, o b t sistances are connected between the capacitance, l5 alternating current systems, by shifting the the inductance and the other terminal of the phase of the potentials applied to the control Winding to establish a range of phase shift of members or grids of the electric valves with ret ltage impre d 0n e Output r uit. spect to the applied anode-cathode potentials. In er embodi t of y invention. I p

Various arrangements have been provided herevide a p ase hifting circuit of the static im- 20 tofore to efiect this phase shift of the grid popedance type Wh c comprises an electric nettential. Static phase shifters, that is, electric work f the bridge yp in which pp i e arms circuits including various combinations or reare of the iv yp and n w h other pp sistance, inductance and capacitance, have proved s e a s are f t resistive typ he reactive 26 to be most satisfactory from the standpoint of branches of the network y be inductances or simplicity, economy and reliability. In view of eapaciteneesone P Of pposite J'u ctu es of t peculiar t b t of phase shifting 1 the reactive elements and the resistances is concuits of the static type, there has been evident nected to terminal connections of Winding a decided need for improved circuits of this nawhich is energized m an alternat ng current 30 ture which are simple in construction and arcircuit, and the other pair of opposite .i e 30 rangement and which employ a minimum nu of the reactive elements and the resistances are her of impedance elements. connected to a resistance'of a voltage divider.-

It is an object of my invention to provide a The resistance of the voltage divider is providnew and improved electric circuit. ed with an intermediate point which is connect- It is another object of my invention to proed to one of the terminal Connections of the 35 vide a new and improved electric phase shifting Winding, d the a ce of t e voltage dividcircuit of the static impedance type. er is each provided with a movable or adjustable It is a further object o! my invention to procontact member in operative relation with the vide a new and improved static impedance phase resistance. An output circuit is connected to an 40 shitting circuit for controlling electric power conintermediate connection of the winding and the 40 verting apparatus. movable contact member of the voltage divider.

According to the illustrated embodiments of F r a better understanding f my inv n i n. my invention, I provide static phase shifting cirreference may be had to the following description cuits for producing an alternating voltage varltaken in connection with the accompanying 5 able in phase with respect to the voltage of an drawing and its scope Will be P d out in the 5 alternating current circuit. The phase shifting pp nd d claimse- 1 d a rammatically illuscircuit includes a winding which is energized t s an ent of my invention as applied from the alternating current circuit, and the 0 an electric Valve Power converting y m and winding is provided with a pair of terminal con- Fi 2 repr n rtain pe i haracterisnections and a resistance electrically lntermeditics thereof. Figs. 3, 4 and 5 diagrammatically 50 ate the terminal connections. A pair of electric illustrate further modifications of my invention. circuits is connected to one of the terminal con- Fig. 1 of my invention is diagrammatically ilnections, and one of the electric circuits includes lustrated as applied to an electric valve power an inductance and the other includes a capaciconverting system for transmitting energy betance. A voltage divider including a resistance is tween an alternating current circuit I and a di- 65 rect current circuit 2 through a transformer 3 and electric valve means 4 and 5. Electric valve means 4 and 5 are preferably of the type employing an ionizable medium, such as a gas or a vapor, and each includes an anode 6, a cathode l and a control member or grid 8 which controls the conductivity of the electric valve.

I provide a phase shifting circuit 9 of the static impedance type, which includes a winding III which is energized from the alternating current circuit I. Winding iil is provided with connections H and i2 and a connection I3 which is electrically intermediate the connections ii and I2. While for the purposes of illustration I have shown the connections M and 62 as being located intermediate the ends of the winding id, it is to be understood that these connections may be located at the ends of the winding and may be considered as terminal connections. A pair of electric paths is connected. to one of the terminal connections, as for example connection i2; one of the paths includes a capacitance is and the other path includes an inductance is. A voltage divider i8 is interposed between the pair of electric paths and the connection it and includes a resistance element ll having terminal connections it and i9. Terminal connection i8 is connected to capacitance id, and terminal connection is connected to inductance i5. Resistance ll is also provided with an. intermediate point or connection Ell which is connected to connection it of winding id. An adjustable or movable contact member 25 is provided in operative relation with resistance H. An output circuit 22 is connected across the intermediate connection it and the movable contact 2i of the voltage divider Resistance ll, capacitance id and inductance i5 may be proportioned to determine the range of phase shift. By the proper proportionlng of these elements, the volt age of circuit may be varied in phase through regions of very small angular displacement to substantially s60 electrical degrees. The range of phase shift obtained is increased by increasing the value of the resistance ll relative to the ohmic values of the capacitance i8 and iuductance Excitation circuits 23 and 2d are associated with electric valve means G and respectively, and impress on the associated control members 8 periodic or alternating voltages which control the conductivities of the electric valves. Each of the excitation circuits and 26 may include means such as a saturable inductive device which produces an alternating voltage of peaked wave form. Each of the saturable inductive devices 25 includes a core member 26 having a shunt magnetic path '2'], a restricted saturable portion 28, a primary winding 29 which is connected to circuit 22, and a secondary winding 39 which is associated with the restricted saturable portion 28 and which produces an alternating voltage of peaked wave form. Any suitable means such as a battery 3! may be employed to impress on the associated control member 8 a negative unidirectional biasing potential, and a current limiting resistance 32 may be connected in series relation with the associated control member.

The operation of the embodiment of my invention shown in Fig. 1 will be explained by considering the electric valve system when power is being transmitted from the alternating current circuit l to the direct current circuit 2 through transformer 3 and electric valve means I and 5.

It is well understood by those skilled in the art that the average voltage impressed on circuit 2 is maximum when there is substantial phase coinci-- dence between the voltages impressed on the control members 8 relative to the applied anode-cathode voltage. That is, the voltage impressed on circuit 2 is maximum when the electric valve means 4 and 5 are rendered conductive at the beginning of the positive half cycles of applied anode-cathode voltage. When the load connected to circuit 2 is inductive, the average voltage impressed thereon will be minimum when the electric valves are rendered conductive at substantially the 90 lagging position with respect to the anode-cathode voltage. Of course, the average voltage impressed on circuit 2 will assume corresponding values for intermediate phase relationships between the voltages impressed on the control members 8 and the voltages applied between the anodes and the oathodes of the electric valves.

The phase oi the voltage impressed on circuit 22 and hence the phase of the voltage impressed on control members 8 of electric valves 1 and 5 is controllable by operation of the movable contact member 2i of the voltage divider id in phase shifting circuit 9. For example, ii it is desired to eilect a progressive advancement in phase of the alternating voltage or peaked wave form. impressed on control members 8 of electric valves 4 and 5, the movable contact member 20 is initially placed in engagement with terminal E8 of resistance ll and is moved in a counterclockwise direction. The alternating voltage impressed on the output circuit 22 is progressively advanced in phase with respect to the alternating voltage of circuit 1! or withrespect to the alternating voltage applied towinding iil. The range of phase shift for such operation of the movable contact member ii is determined by the relative ohmic values of resistance il capacitance i l and inductance iii.

For a more complete explanation of the manher in which the phase shifting circuit operates, reference may be had to the operating characteristics shown in Fig. 52. For a particular set of values for resistance 5?, capacitance and inductance i the vector AB represents the voltage appearing between terminals it and 12 of winding it} and the vector CB represents the voltage appearing across the terminals of the capacitance id. The vector AC represents the voltage appearing across that portion of the resistance ll of voltage divider which lies between the intermediate point and the terminal i Vector DB represents the voltage appearing across the terminals of inductance i5 and vector AD represents the voltage appearing across the terminals of the portion of resistance ll lying between the intermediate point 28 and terminal [9. The point 0 represents the potential of the intermediate connection 63 of winding 40. The vector 0C represents the voltage impressed on the output circuit 22. When the movable contact member 2| is in engagement with the terminal I8 of resistance H, the voltage impressed on the output circuit 22 has a phase position corresponding to the position of vector OC. As the movable contact member 2| is rotated in a countor-clockwise direction, the vector 0C assumes the positions OE, OF and 0G. When the movable contact member 2| is in engagement with the intermediate point 20 of resistance H, the vector representing the voltage impressed on circuit 22 coincides with the vector 0A. For pro- 'ticularly adaptable for shitting the phase the gressive movement of the movable contact member 2| in the counter-clockwise direction, the voltage impressed on the output circuit 22 progressively assum'es phase positions corresponding to vectors OI-I, OJ and OK, and when the movable contact member 2| engages terminal I! or resistance H the voltage vector of circuit 22 coincides with the vector CD. It will be noted that ior the particular vector diagram shown, the phase of the voltage impressed on circuit 22 .has been varied through substantially 180 electrical degrees. 01 course, it is to be understood that the range or phase may be increased or decreased by. the proper choice of values for resistance l1, capacitance l4 and inductance II. For example, by increasing the value of the resistance I! so that the vector diagram 01 the phase shifting circuit includes the triangles ALB and AMB, the output voltage may be rotated counter-clockwise from the position 0L to the position OM, and the voltage impressed on circuit 22 may be varied in phase from the position indicated by vector 0L to the position of vector OM, which is a range substantially in excess of 180 electrical degrees.

In Fig. 3 of the accompanying drawing there is illustrated'a modification of the embodiment of my invention shown in Fig. 1, and corresponding elements have been assigned like reference numerals. To control the range of phase shift of the voltage impressed on output circuit 22, I provide a pair of movable impedance elements, such as adjustable resistances 33 and 34, which are connectedbetween the pairs of electric circuits and the terminal connection ll of winding ill. The adjustable resistances 33 and 34 serve as an agency for controlling the maximum range of phase shift occasioned by moving the contact member 2| over the resistance I1.

The operation of the embodiment of my invention shown in Fig. 3 is substantially the same as that explained above in connection with the arrangement of Fig. 1. The resistances 33 and 34 may be adjusted to establish the range of ments, such as capacitances 36 and 31, and opposite resistive branches include resistances 38 and 39. One pair of opposite junctures oi! the resistances and capacitances, such as junctures 40 and 4|, are connected to terminal connections II and .I2 of winding l0, and the other pair of junctures 42 and 43 are connected to terminals l8 and I9 of the resistance T1 of the voltage divider IS. The intermediate point 20 0f the resistance I! is connected to juncture 4| and terminal connection l2 of winding H).

The phase of the alternating voltage impressed on circuit 22 may be progressively advanced by moving the contact member 2| from the terminal I3 of resistance l'l to the terminal I9 01 this resistance. This arrangement permits smooth and continuous control of the phase of the output voltage over ranges extending from substantially 360 to very small angular displacements.

In Fig. 5 there is diagrammatically illustrated another embodiment of my invention which is similar in many respects to that shown in Fig. 4. The arrangement in Fig. 5 is parvoltage of circuit 22 within a region or range or substantially 380xelectrical degrees. A voltage divider 44 is provided with a resistance 44 which is connected to the bridge circuit 33 and the winding III. Terminal connections 43 oi resistance 43 are connected to juncture 43 of. the

bridge 33 and to terminal oi! winding Ill. Point 41 is connected to 'iuncture '40 0! bridge 33; point 48 is connected to juncture 42 and to terminal |2 of winding Ill; and point 43 is connected to juncture 4|.

A movable contact member- 40 is operatively associated with resistance 43 and serves to shift the phase of the voltage impressed on output circuit 22 which is connected between the movable contact 50 and intermediate connection l3 of winding 14.

By rotating the contact ill of the voltage divider 44, the voltage impressed on circuit 22 may be progressively advanced or retarded in phase throughout a 360 electrical degree range; The shift in phase of the voltage of circuit 22 is continuous and smooth throughout this range.

Certain features of the modifications of my invention shownin Fig. 4 and Fig. 5 are disclosed and claimed in divisional application, Serial No. 340,758, and which is assigned to the assignee of this application.-

While I have shown and described my invention as applied to a particular system of connec-' voltage variable in phase relative to the voltage of said alternating current circuit and of substantially constant magnitude and comprising a winding energized from said circuit and having a pair or terminal connections and an electrically intermediate connection, a pair of electric paths connected to one of said terminal connections, one of said paths including a capacitance and the other including an inductance and a voltage divider including a resistance connected across said paths, said resistance having an intermediate point connected to the other terminal of said winding and having a single movable contact for shifting the phase of said alternating voltage through substantially 180 electrical degrees, and an output circuit connected across the intermediate connection of said winding and said contact of said resistance.

2. In combination, an alternating current circuit, apparatus for producing an alternating voltage variable in phase relative to the voltage of said alternating current circuit and or substantially constant magnitude and comprising a winding energized from said circuit and having a pair of terminal connections and an electrically intermediate connection, a pair of electric paths connected to one or said terminal connections. one of said paths including a capacitance and the other including an inductance, a voltage divider including a resistance connected across said paths and having an intermediate point connected to the other of said terminal connections and a single movable contactor in operative relavoltage variable in phase relative to the voltage of said alternating current circuit comprising a winding energized from said circuit and having a pair of terminal connections and an electrically intermediate connection, a pair of electric paths connected to one of said terminal connections,

one of said paths including a capacitance and the other including an inductance, a voltage divider including a resistance connected across said paths, said resistance having an intermediate point connected to the other terminal of said winding, impedance elements connected between said paths and said other terminal for controlling the range of phase shift of said alternating voltage, and an output circuit connected across the intermediate connection of said winding and said voltage divider.

4. In combination, an alternating current circuit, apparatus for producing an alternating voltage variable in phase with respect to the voltage of said alternating current circuit comprising a winding energized from said circuit and having a. pair of terminal connections and a connection electrically intermediate said terminal connections, a pair of electric circuits connected to one of said terminal connections, one

or said circuits comprising a capacitance and the other comprising an inductance, a voltage divider including a resistance connected across said paths and having an intermediate point connected to the other of said terminal connections, adjustable resistances connected between said paths and said other of said connections to establish the range of phase shift of said alternating voltage, and an output circuit connected across the intermediate connection of said winding and said voltage divider.

5. In combination, an alternating current circuit, apparatus forproducing an alternating voltage variable in phase relative to the voltage or said alternating current circuit comprising a winding energized from said circuit and having a pair of terminal connections and a connection electrically intermediate said terminal connections, a pair of electric paths connected across said terminals, qne of said paths including a serially connected capacitance and a resistance and the other of said paths including a serially connected inductance and a resistance, a voltage divider including a resistance connected between junctures of the resistances and the capacitance and the inductance in said pair of circuits, said resistance of said voltage divider being provided with an electrically intermediate point connected to a common juncture of the resistances in said pair of paths, and an output circuit connected across the intermediate connection of said winding and said voltage divider.

GEORGE W. GARMAN. 

